A novel shape descriptor, termed multi-scale bisector integrals, is proposed in this paper. Different from the existing Radon transform based descriptors which integrate the shape image function over all the possible lines in its domain, the proposed method restrains the integrals only over a special class of lines, termed shape bisectors, for characterizing the essence of the shape. Integrating the shape image over the multi-orders of shape bisectors yields a multi-scale descriptor. The proposed descriptor is completely invariant to translation, scaling and rotation. The experimental results on the standard MEPG-7 CE-2 shape database demonstrate its superiority over the state-of-the-art approaches.